The invention relates to a start-stop device for initiating an automatic switch-off procedure of a drive machine in a motor vehicle.
At present, internal combustion engines are usually switched off manually by the driver by means of an ignition key or by means of actuating an operating element. One exception is a method that is proposed in DE 100 23 331 A1. In said method, the brake pedal position or the brake pedal pressure is evaluated in lieu of the ignition key. The switch-off procedure of the internal combustion engine is initiated if, after the motor vehicle is brought to a standstill, the brake pedal is actuated more intensely in its already actuated position. In order to drive on, the brake pedal is released and the gas pedal is pressed as a result of which a procedure of starting the internal combustion engine is initiated. The disadvantage with methods of this type is that the driver of the motor vehicle is solely responsible for switching off the internal combustion engine. Analyses of modern driving behavior indicates that despite increased environmental awareness and increased fuel prices, a manual switch-off procedure of the internal combustion engine, for example at traffic lights, is seldom performed independently.
In order to reduce fuel consumption and pollutant emissions, vehicles are already provided with systems that automatically switch off the internal combustion engine of a motor vehicle in specific circumstances or if predetermined switch-off conditions are present and said systems automatically switch said internal combustion engine back on if predetermined switch-on conditions are present. Methods and systems or start-stop devices of this type are suitable above all for urban traffic for reducing the consumption of fuel since in urban traffic the vehicle often comes to a standstill at traffic lights or on account of the traffic and the operation of the internal combustion engine is not required.
At present, various switch-off and switch-on algorithms having different advantages are used by individual vehicle manufacturers. Vehicles having automatic transmissions are thus on the market in which the engine is automatically switched off if the driver has braked the vehicle to a standstill. The engine is restarted as soon as the brake pedal is released. Another switch-off algorithm in the case of automatic vehicles provides that the engine is only switched off after approximately 1 second after the vehicle has been brought to a standstill.
Furthermore, DE 10 2010 000 615 A1 discloses an automatic switch-off algorithm for automatic vehicles, wherein the engine is switched off if it drops below a predetermined speed (for example 20 km/h). If during the further progression of time, in other words while the engine is off, a zero speed is measured (actual speed may not be the same on account of sensor inaccuracies), a brake controlling procedure is built up by successively increasing the braking force so as to maintain the vehicle at a standstill.
Finally, DE 10 2014 206 509 A1 discloses a start-stop system for a motor vehicle, wherein the engine may be operated in two different stop-start operating modes having different switch-off conditions in which the engine is stopped if the respective stop conditions are fulfilled. The stop-start operating mode that is to be used is selected by means of a user input device that is to be actuated by the driver, in other words the driver selects which start-stop operating mode is applicable and is to be implemented.
It follows from this that the object of the invention is to provide a start-stop device that renders possible an improved adjustment of the switch-off procedure to the current situation.
This object is achieved in accordance with the invention by a start-stop device for initiating an automatic switch-off procedure of a drive machine in a motor vehicle, said start-stop device being configured so as to automatically switch off the drive machine if predetermined switch-off conditions are fulfilled, characterized in that the start-stop device comprises a stop coordinator that, based upon the prevailing information, identifies a switch-off behavior that is suitable for the switch-off procedure and, when initiating an automatic switch-off procedure, ensures that the identified switch-off behavior is achieved.
The invention is based on a fundamentally known start-stop device for initiating an automatic switch-off procedure of a drive machine in a motor vehicle, said start-stop device being configured so as to automatically switch off the drive machine if predetermined switch-off conditions are fulfilled. In particular, the automatic switch-off procedure of the drive machine may be initiated in the prevailing switch-off conditions either while the vehicle is (still) in motion (for example at low speeds) or while the vehicle is already at a standstill or almost at a standstill.
The invention is furthermore based on the knowledge that with regard to the shut-down behavior during known shut-down procedures a conflict of objectives may occur between shut-down comfort with shut-down time, ability to restart and engine shut-down position since, depending upon various constraints, a different shut-down behavior may be advantageous. The object of the invention is consequently to provide a system that independently solves this conflict of objectives.
In taking into account the above consideration, the invention provides a start-stop device for initiating an automatic switch-off procedure of a drive machine in a motor vehicle having an automatic transmission, an automated transmission or a manual transmission, wherein the start-stop device comprises a stop coordinator that, based upon the prevailing information, identifies a switch-off behavior that is suitable for the switch-off procedure and, when initiating an automatic switch-off procedure, ensures that the identified switch-off behavior is achieved.
In particular, the stop coordinator may be configured for this purpose so as to select a suitable stop operating mode that is to be initiated from at least two stop operating modes having respectively defined different switch-off behaviors depending upon prevailing information or operating parameters of the motor vehicle and, corresponding to the selected stop operating mode, to trigger an automatic switch-off procedure of the drive machine in order to achieve the associated switch-off behavior. The different stop operating modes may be configured in such a manner that they are fundamentally based on the same switch-off conditions but differ in the switch-off behavior or that these stop operating modes differ both in the case of the necessary switch-off conditions as well as in the switch-off behavior.
In a further advantageous embodiment of the invention, it is provided that there is no operating element by which the driver may himself in advance set or select a suitable switch-off behavior or a stop operating mode having defined shut-down behavior, in other words the selection is always performed by means of the stop coordinator. On account of the conflict of objectives during the shut-down behavior between more than two possibilities for one shut-down behavior, it may be provided that the stop coordinator is configured, depending upon the prevailing information, in particular the prevailing operating parameters of the vehicle, to select a stop operating mode that is to be initiated from at least three possible stop operating modes having different shut-down behaviors and, corresponding to the selected stop operating mode, to trigger an automatic switch-off procedure of the drive machine in order to achieve the associated switch-off behavior.
In tests, this has shown that at least one shut-down behavior that is to be identified, in particular the different shut-down behaviors of the possible stop operating modes, may be characterized as follows:
(1) Comfort-oriented shut-down behavior in which the drive machine is switched off as comfortably as possible or as quietly as possible. The focus is not to switch off the drive machine rapidly but rather to switch off the drive machine as comfortably as possible.
(2) Reflex start time-oriented shut-down behavior in which it is possible to restart the drive machine during the deceleration phase of the drive machine without the use of a starter for as long as possible. This shut-down behavior is particularly suitable if a so-called change of mind case (driver would actually like to drive on) is to be expected or possibly occurs.
(3) Shut-down position-optimized shut-down behavior in which it is possible to restart the drive machine as rapidly as possible or in an optimal manner after successfully switching off the drive machine/when the drive machine is at a standstill.
Corresponding information must be provided to the stop coordinator so that the stop coordinator may decide which shut-down behavior or which stop operating mode having the corresponding shut-down behavior appears to be most suitable at the actual point in time and is to be triggered. The stop coordinator is advantageously configured, depending upon prevailing information that describes the prevailing driving situation of the motor vehicle, so as to identify a suitable switch-off behavior for the switch-off procedure, in particular to select a stop operating mode that is to be initiated from the possible stop operating modes having different shut-down behaviors. The information that describes the prevailing driving situation may be prevailing operating parameters of the motor vehicle and/or prevailing information regarding the surrounding area (other road users, traffic management, road class, weather, time of day) and/or prevailing information regarding the driver (behavior, attention).
In a particularly advantageous embodiment of the invention, the stop coordinator is accordingly configured, depending upon prevailing information that provides information regarding the speed (rolling, at a standstill) and/or information regarding whether the transmission is operated with traction or without traction, so as to identify a switch-off behavior that is suitable for the switch-off procedure, in particular to select a stop operating mode that is to be initiated from the stop operating modes having different shut-down behaviors.
It is likewise possible, when making a decision regarding a suitable shut-down behavior, for information regarding energy consumers in the vehicle to be taken into account, in other words the stop coordinator may be configured so as to identify a switch-off behavior that is suitable for the automatic switch-off procedure taking into account at least information regarding auxiliary units or energy consumption of the vehicle, in particular regarding the prevailing or requested operating state and/or energy consumption of at least one auxiliary unit, in particular to select a stop operating mode that is to be initiated from the different stop operating modes having different shut-down behaviors.
In order to be able to achieve the identified shut-down behavior, the stop coordinator is advantageously configured to trigger or influence for the identified shut-down behavior, in particular according to the selected stop operating mode, a parameterization, which is predetermined for the selected stop operating mode, for at least one of the following actuating and/or closed-loop control functions or to influence their parameterization:
(1) Crankshaft shut-down position
(2) Function for influencing the ability to restart the drive machine while the drive machine is decelerating,
(3) Rotational speed reducing function,
(4) Air volume closed-loop control function,
(5) Auxiliary units actuating function, in particular function for actuating the generator and/or the air conditioning device of the motor vehicle, in particular the coupling of the air conditioning device, and/or
(6) Function for influencing the comfort-oriented shut-down behavior.
In a similar manner to the start-stop device that is proposed here in accordance with the invention, a corresponding method for initiating an automatic switch-off procedure of a drive machine may be embodied in a motor vehicle so as to switch off the drive machine automatically if predetermined switch-off conditions are fulfilled, wherein based upon the prevailing information a switch-off behavior that is suitable for the switch-off procedure is identified and when initiating an automatic switch-off procedure it is ensured that the identified switch-off behavior is achieved. Advantageously, depending upon prevailing operating parameters of the motor vehicle, a stop operating mode that is to be initiated may also be selected from at least two different stop operating modes having respectively defined (different) shut-down behavior and according to the selected stop operating mode a procedure of automatically switching off the drive machine is triggered in order to achieve the associated switch-off behavior.
Further advantageous embodiments of the start-stop device in accordance with the invention also apply for the method in accordance with the invention and said method may be implemented in a suitable control device, in particular in an engine control unit.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.